Expansion drill bit



Dec. 8, 1931. A. c. ARTHUR ET AL EXPANSION DRILL BIT Fi led May 28, 1928 gwuanto'cs Patented Dec. 8, 1931 UNITED stares ;rArENr r ce ALAN o. anrnuaann o'rro r. LAMrsorr, or VENTURA, CALIFORNIA EXPANSION DRILL BIT Application filed ma as Our invention relates to earth boringfools, and more particularlyto rotary drill its in which-a set of pivoted cutter blades are adapted to be expanded to operative orcutting position, there being means associated with said it whereby chattering of said blades is effectively prevented when], said bit is being tivelycooling said blades and sweepingaway the cuttings formedby said blades, thejcut ting edge of at least. one of said blades-being extended inwardly to the centerof said bit. to cut the earth stratum infthe center below said bit to avoid centering thereof.- r f It is also within the province of our invention to slightly incline the cutting edge of each blade from the outer to the inner edge 2 for more effectively cutting the earth stratum, the cutting edge of said blades, if preferred, being of different lengths and symmetrically positioned with respect to the bit.

The (bove and ffrther objects and advan tages of our invention, as will'hereinafter more fully appear, we attain by the construc tion described in the specification, and illus-' trated on the drawings, forming a part of our application. i

Reference s "had to the accompanying drawings, in which'similarreference charac ters denote similar parts. I In the drawings,

Fig. 1 is an elevational view of'our invention showing the pivoted cutter blades in expended position, I i

Fig. 2 's' a bottom plan view of Fig. 1,

Fig. 3 is a fragmentary elevational View showing the cutter'blades in retracted position,

Fig. 4 is afragmentary cross-sectional View illustrating the wedging or eccentric action of the blades in their sockets, and

Fig. 5 is a similar view takenat a right angle to Fig. 4.

Describing our invention more in detail,

1928. Serial No. 280,975.

thebody portion 2 is preferably tapered as at 4 and has extended therefrom a shank 6, provided with a tapered extension 8 having threads 10 to whichmay be secured a means for rotating the 'bit.

The body portion 2 is cut away as at 12 to provide a set of sockets in which are positioned the cutter blades 14, preferably three in number, and pivoted insaid sockets by any suitablemeans,such as the bolts 16, the body portion 2; being cut away as at 18 to accommodate said bolts or pivoting means, said body portion being also cutaway as at 20 to provide for a ready disposal of the cuttings of the blades 14. v v i As seenin the drawings, the cutter blades 14 are of difi'erentrwidth s, although said blades may be of the same width, if desired,

and the cutting edge 22 of each of said blades ispreferably slightly inclinedfrom theouter. edge thereof inwardly to the inner edge. as seen more particularly in Fig l, for the purpose of more effectively cutting the earth formation and to provide for even r wear of the blades. It will also be observed that at least one of the blades14 has its inner edge extending to the center of the bit for the purpose of cutting away the earth stratum at that point to avoid, buildingup at the earth stratum and thus avoid item 0 tering of the bit so that a straight hole may be cut. i

To provide a means for sweeping the cut tings from the bit and blades, and also to cool said blades, the bit is providedwith a central circulating medium passage 24 con- I 'nec'ted with branch passages 26 leading to outlets28 positioned forwardly of the blades 14. See Figs. 1 and 2. i

4), and the tops of each blade are also curved m9 as at 34, longitudinally, and transversely as at 36, but on diiferent radii so that the tops of the blades will be eccentric with relation to the tops of the sockets. This will provide an increasingly wedging action as the blades 14 are expanded so that chattering will effectively be prevented in said position.

If desired, the blades 14: may be provided with a suitable means for limiting the extent of their inward movement, such as the shoulders 38, which shoulders are adapted to engage the body 2 for this purpose. See Fig. 4.

Vhile we have thus described our invention with great particularity, it will be clear that the same may be modified "throughout a wide range. YVe accordingly .do not propose to be limited to the .exact details of construction .described and claimed, but reserve the right in practice .to make any and all modifications thereof that fall within the scope of theappended claims.

We claim as our invention:

.1. A rotary .drill bit including a threaded shank zand ra body portion, d body portion being provided with a set of independent sockets, said sockets being each eurvedaat their top portions, and a cutter blade pivotally positioned in each of said sockets, .each ofsa id blades being curved at its top portion, but on diiferent radii than the curved parts of said sockets whereby .a wet 'ingaction "is had as said blades are expanded.

2. A rotary drill bit including a threaded shank and a body portion, said body portion being provided with a set of independent sockets having curved top portions, and a set of cutter blades pivotally associated with said sockets, said blades being each cuteaway at their top portions well as their edges, whereby a wedging action may be maintained between said blades and said sockets when said blades are expanded into cutting position.

3. A-drill bit including a screw-threaded shank and a body portion, said body portion being provided with a set of independent sockets, a cutter blade pivotally positioned in each of said sockets, the top of each ot said blades being positioned ineccentric relation with the top of each of said sockets, whereby a wedging action may be-had therebetwcen when said blades are expanded, and means associated with eachot sait blades and said body portion for limiting the in ward position of each of said blades.

4. A drill bit including a shank and ,abody portion, said body portion provided with a setot independentsockets and a cutting blade pivotally ,positionedin each of said sockets, said blades having cuttin edges of different lengths and slightly inclined from the outer edge to the inner edge, at least-one of saidblades extending inwardly beyond the others to cut the :formation in the center of the bit.

5. A drill bit including a shank and a body portion, said body portion being provided with a set of independent sockets, and a cutter blade, pivotally positioned in each of said sockets, the inner cutting edge of at least one of said blades extending to the cen ter of said body portion whereby the earth formation may be effectively cut in the cen ter to avoid centering of said bit in said f0rmation.

'6. Ina rotary drill bit, a body, means on said body whereby it may be attached to a string o f pipe, said body being provided with cut-away portions for the disposal of the cuttings and a set of independent slots, a cutter blade ineach of said slots, and pivotal means for each of said blades insertable through said blades in said cut away portionssa-id blades being adapted to be sprezul out from .said body as said bit is operated,

at leastone ofsaid blades extending .inwardly beyond the others to cut the formation in the center of the bit.

-7. A rotary drill bit comprising a body portion having a set of independent slots extending in a substantially radial direction from :the outer periphery ofsaid body portion, and a cutter blade pivotally mounted in each of said slots, and in off-set relation therewith, the inner end of at least one of said blades extending inwardly a substantial distance beyond the inner ends of each of the .other of said blades.

8. In arota-ry drill bit, a body portion provided with a set of independent and spaced apart radial slots, an angular :cutter hlade each having acurved portion, pivot-ally mounted in each of saidislots, each of said blades being adapted to have its angular portion spread from said body portion .as said bit is-operated, at least onezof said blades extending beyond the others to cut the formation at the .centero'f the bit.

9. A drill bit including a shank and a body portion cut away for the disposal of the cuttings, said body portion being provided with a set of independent and spaced apart radial slots, a combined curved .and angular cutter blade pivotally mounted in each of-said slots, said blades, when said bit is operated, being adapted to be spread out from said body portion, but when at rest being positioned substantially within the confines of said body portion, said cutter blades having cutting edges 01" unequal length.

In testimony whereof we have signed. our names :to this specification.

ALAN C. ARTHUR. OTTO P. LAMPSON. 

